Jet bandsaw motor replacement

This is not so much a review of my bandsaw, as a discussion of issues I had with the motor, and the struggle I went through replacing it. I had origionally posted this under ‘projects’, but some folks had suggested it really belonged under ‘reviews’. So here it is.

While re-sawing some 10” wide Walnut boards, I managed to blow out the motor on my bandsaw. The local repair shop could not fix it (they claimed it was a cheap motor, and not repairable). Jet wanted almost $400 for a replacement motor, which I thought was a bit steep for a not so great motor, with no thermal protection at all (which would have saved the motor).

So I shopped around for another motor that I could make fit. In the process, I learned WAY more about both American (NEMA) and International (IEC) motor standards than I ever thought I would need to know. I also learned that Jet’s motor does not adhere to either standards, so common off the shelf motor are not a drop in replacement. Dang those Jet people, and their proprietary motor mounts.

But I figured out a way, with lots of drilling and finagling, to get a much better and less expensive standard NEMA motor to fit. Plus it’s a more powerful motor to boot. Now I can resaw the thick walnut without the motor straining at all.

The fact that the motor blew out to begin with is mostly my fault. I had been resawing for a few hours, and had not stopped to notice how dull the blade was getting, or how hot the motor was. If I had stopped to sharpen the blade, and let the motor cool down, it would not have blown out so bad.

I am however, a little disappointed in the motor that came with the saw did not have any kind of thermal protection (which is a pretty standard feature in good quality motors), with the overall build quality of the motor, and that it uses a proprietary mounting pattern.

I have also always had issues with the motor bogging down while resawing thick hardwood. So I think the original motor was a little underpowered for my needs. I did notice that my model bandsaw now ships with a 3hp motor, instead of the 1.5hp mine came with. So perhaps Jet realized there was an issue with the 1.5hp motor they used to ship, and have worked to correct the issue. I hope that is the case.

Other than the motor adventure, I’ve been pretty pleased with the saw. Once tuned up, I can resaw very thin veneers from 10” wide hardwood boards, then switch blades and cut very accurate detailed cuts.

As mentioned, the motor was from www.surpluscenter.com. I’m very pleased with my dealings with them. The motor I ended up with was under $100, and is a little on the cheap side (the flan blade, and the junction box are plastic for example). However, the motor seems to be quite a bit beefier than the original Jet motor. So at least it’s a step up. I see now that surpluscenter has a nicer c mount motor in stock for about $200. If this were available when I ordered mine, I think I would have gone that route.

Before going the surpluscenter route, I looked around locally for a good used engine. The issue is that I needed a face mounted (C mount in NEMA terms). Base mounted motors are available everwhere. Face mounted motors are a bit harder to find.

-- Andy -- No animals were harmed in the posting of this entry, although the terrier next door is living on borrowed time, let me tell you.

Yes, it turns out sharpening bandsaw blades is fairly easy. I discovered this once I found my blade was dull, and did some internet research to determin what my options were. Just do a youtube search on “Sharpening bandsaw blades”, and you will see quite a few videos on the topic.

kayakguy,I thought I would chime in on this because you mentioned the 3hp motor Jet now offers which I’ve owned for a few months. I do think Jet realized the 1.5 hp might be under powered for resawing. I can tell you with a WoodSlicer blade I haven’t been able to bog down the 3hp model – however, I haven’t run the saw for more than probably 30 minutes continuously either.

Edit: I should point out that I purchased my saw from Rockler and at the time the 3hp motor was only $100 more than the 1.5 hp.

Like I said, I knew nothing about this stuff when I started out replacing the motor. Here is what I have gathered while doing my research. If any electrical engineers out there wish to correct my understanding, please feel free.

NEMA (National Electrical Manufacturers Association) and IEC (International Electrotechnical Commission) have both created a set of standards of motor mounting, output, and efficiency. It’s the motor mounting standards I was most interested in. Both standards specify things like mounting type, mounting bolt pattern, output shaft size, shaft length, shaft key size, etc. The idea is that if you design an application for a specific NEMA or IEC motor type, you can then go to any motor manufacturer and buy a motor matching that spec.

Neither spec states anything about motor quality. You can buy crappy made motors that follow IEC sizes, as well as NEMA sizes. Most motor manufacturers it seems make motors for both specs, which makes sense. Why loose out on the rest of the world if you make motors in the US, just because the US uses NEMA. Conversely, if you are an overseas manufacturer you can not afford to miss out on the US market.

Here is a spec chart for both IEC and NEMA motor sizes (called frame sizes in the specs)www.baldor.com/pdf/501_Catalog/BackCover.pdf

Both specs list a couple of different motor mounting types. Base type, where there is a mounting bracket on the base of the motor, and face mounted, where the face of the motor has several threaded mounting holes (in NEMA terms, this is called a C mount).

The base mount motors are the most common. For woodworkers, you most commonly see these in table saws, and many bandsaws (my drill press uses a base mount motor as well). Because they are so common, base mount motors tend to be much cheaper. I’m not sure they are really any cheaper to make, it’s just that there are so many manufacturers making them.

The face mount (or C mount) is much less common (unfortunately for me), and is therefore tends to be more expensive.

In my case, I could find plenty of base mount motors in used shops, pawn shops, etc here where I live.

So to find out if your motor fits any of the NEMA or IEC specs, look at the charts, and see if the shaft size, shaft length, etc fit any of the types listed. Be careful. Some of the IEC frame sizes (which are in metric) are dangerously close to some of the NEMA sizes. So if you measure your shaft and it seems “close to 7/8”, but not quite” for example, then it may be IEC, and more exactly match the metric dimensions.

It seems like the most common NEMA size is the 56 (for base mount) or 56C (for face mount). From the chart, you can see the 56 motor has a 5/8” shaft, that is 1 7/8” long. The keyway is 3/16” wide, and 1 3/8” long. In the ‘C’ version the mount/bolt pattern is 4 holes evenly spaced on a 5 7/8” diameter hole.

Most of the motors I looked at stated the NEMA or IEC frame size on the motor in some way. They would say something like “NEMA 56C”, or “IEC 71”.

In my case, the old JET motor had a shaft who’s diameter matches one of the IEC sizes. However, shaft length, and mount pattern did not match any of the IEC motor specs. I might have been able to make an IEC motor fit, but IEC C mount motors are extremely hard to find in the US, and with the sources I could find they were much more expensive than NEMA motors. I ended up getting a NEMA motor, buying a new belt pulley to match the shaft diameter of the new motor, then drilling holes in the side of my bandsaw to match the mounting pattern of the motor I got.

Whew, lots of pointless blather about motors. You can relax, I’m tired of typing now. Hope this helps

-- Andy -- No animals were harmed in the posting of this entry, although the terrier next door is living on borrowed time, let me tell you.

$462, ouch! I just checked surplus center again, to see if the same motor I bought was still there. It seems they have seriously reduced their inventory of c-face motors. They used to have several pages of c-face motors, and now they only have a handfull. It’s too bad. It’s been over a year, I’m still very happy with the $100 motor I picked up from them. The motor I picked up from them was only 2hp. However, I have never bogged it down, like I have the origional Jet 1.5hp motor. So 2hp seems sufficiant for my needs – even resawing 10” wide walnut.

Hope you find another motor inexpensive source Lee.

-- Andy -- No animals were harmed in the posting of this entry, although the terrier next door is living on borrowed time, let me tell you.